One of the questions I got asked several times was "so how do I use my blog to sell my product." Apparently, I didn't answer the question very well.
The bottom line is I don't think blogs are the right place to sell products. In fact, I think they're the wrong place to sell. They're a great vehicle for communicating with customers and engaging in the conversation happening on the 'Net about a product, but they're lousy places to sell products. The reason is simple: no one wants to come to your blog and listen to you talk about your product.
One of the points I made several times is that it's a lot easier to make money because of blogging than it is to make money from blogging. The distinction is critical. I've made a lot of money because of my blog. I make very little money from it.
Truth be told, I do use my blog to sell a product: me. You are the easiest product to sell on your blog because your blog will be a reflection of you. If people find it interesting or informative, then they're sold on you.